Name the property under multiplication used in each of the following:
(i) -4/5 × 1 = 1 × -4/5 = -4/5    (ii) -13/17 × -2/7 = -2/7 × -13/17
(iii) -19/29 × 29/-19 = 1

Solution:

(i) -4/5 × 1 = 1 × -4/5 = -4/5

∴ 1 is the multiplicative identity in the above expression.

Thus, the property of Multiplicative Identity is used here.

(ii) -13/17 × -2/7 = -2/7 × -13/17

In general, a × b = b × a for any two rational numbers.

Thus, the property of Commutativity of Multiplication is used here.

(iii) -19/29 × 29/-19 = 1

For a rational number a/b, the multiplicative inverse is the reciprocal of that number which is b/a.

Thus, the property of Multiplicative Inverse is used here.

☛ Check: Class 8 Maths NCERT Solutions Chapter 1

Video Solution:

Name the property under multiplication used in each of the following: (i) -4/5 × 1 = 1 × -4/5 = -4/5 (ii) -13/17 × -2/7 = -2/7 × -13/17 (iii) -19/29 × 29/-19 = 1

NCERT Solutions Class 8 Maths Chapter 1 Exercise 1.1 Question 5

Summary:

The properties used in each of the following: (i) -4/5 × 1 = 1 × -4/5 = -4/5 (ii) -13/17 × -2/7 = -2/7 × -13/17 and (iii) -19/29 × 29/-19 = 1 are Multiplicative Identity, Commutativity of Multiplication, and the Multiplication Inverse respectively.

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